Manifold for internal-combustion engines



May 22. 1928.

A. P. BRUSH MANIFQLD FOR INTERNAL COMBUSTION ENGINES Filed Feb. 11, 1924 PATENT OFFICE.

ALANSQN P. BBU 'SH, OI DETROIT, MICHIGAN.

IANIIOIJ) FOR INTERNAL-COMBUSTION ENGINES.

Application filed February 11, 1924. Serial No. 692,135.

The invention relates to intake manifolds for internal combustion engines employing a mixture of li uid fuel and air and more particularly to t e so-called inlet manifolds, which distribute the mixture produced by the carburetor to the various cylinders. The objects of the invention are: first, to eliminate loading or the retention of a portion of the fuel at one or more points intermediate the carburetor and the inlet valves; second, to produce an even distribution of a homogeneous mixture to the various cylinders; third, to obtain a highly atomized mixture at the inlet valve; fourth, to obtain all of the effects above described without limiting the capacity under full demand and while maintaining the mixture atrelatively low temperature when introduced into the explosion chamber. With these and other minor objects in view, the invention consists in the construction as hereinafter set forth.

In the drawings: Figure 1 is a sectional elevation of a manifold embodying the improvements; Figure 2 is a cross section thereof; Figure 3 is a view similar to Fig. 2 showing a modified construction.

In the operation of internal combustion engines provided with the usual manifold construction there is a great variation in the velocity of the mixture between the throttle and the explosion chamber, so that at low ,velocities loading or the deposit of liquid fuel is a common defect, particularly where the mixture is traveling in an upward direction or against the force of gravity. Suchresult can be partly prevented by providing conduits of relatively small cross sectional area for the conduction of mixture at low engine speeds and by supplementing such conduits with additional conduits, which. may be of larger cross sectional area, which come into use under greater engine demand. This necessitates some means of control such as a valve for opening and closing the secondary conduits and automatic means for actuating the same. It is also essential that the operation of the valve or controlling means should be such as to maintain the required velocity in the primary conduits and only open the secondary conduits as required to supply increased demand. It is not, however, possible to completely prevent the dropping out of sus-' pension of portions of the fuel, particularly upon entering the cylinder block where the passage is necessarily of maximum capacity and where the direction is upward. The

present construction is designed to perform' the functions as required by the conditions above described and to avoid the defects of constructions heretofore used.

I As specifically shown in the drawings, my improved manifold is designed for application to an engine having three separate inlets to the block for supplying the cylinders, as is common practice for six cylinder engines. The same construction is, however, applicable to engines having any number of cylinders or separate inlets for supplying the same. In detail, A is the throttle in the carburetor casing B, and C is a vertical portion of the manifold rising from the carburetor. symmetrically distributed about this vertical portion are pairs of laterally extending conduits which lead to the several inlets to the engine block. Thus as shown there are the conduits D, E leading to the left D, E leading to the right and the conduits D E leading rearwardly to a central inlet in the block. The primary conduits E, E and E are of limited cross sectional area such as to supply the-demand when the engine is idling or operating under light loads and to maintain a sufiicient velocity in current to prevent the dropping of the fuel out of suspension. The secondary conduits. D, D and D together with the conduits E, E and E are of suflicient capacity for the maximum demand, but said secondary conduits are only brought into operatlon when the primary conduits are inadequate.

To control the change from the primary to the secondary conduits, [there is provided a valve F shown in the form of apiston,

on the opposite ends thereof.

With the construction as thus far described it' is obvious that where the throttle is in closed or nearly closed position, the pressure in the manifold immediately above the throttle is not greatly in excess of that in the conduits D and the cylinder G connected therewith so that the piston valve remains in its lower position where the larger conduits are cut off from direct communication with the inlet portion C of the manifold. If, however, the throttle should be suddenly opened, the greatly increased pressure operating upon the lower end of the piston valve over that in the cylinder G operating on the upper end of the valve will rapidly lift said valve. In case of an instantaneous demand not long sustained, there would be danger of opening the conduits D, D and D before needed to supply the demand and the consequent dropping of the velocity in the primary conduits E, E and E Such a result is, however, prevented by providing an additional length to "the piston F so that before the port is opened between the portion C and the conduits D, D and D the vacuum in the cylinder G is satisfied. In other words, the upward movement of the piston in the cylinder will raise the pressure therein until it equalizes the pressure in the portion C and before the passage is opened from said portion C to the conduits D, D and D Nevertheless, if the demand is sustained, the higher vacuum produced in the conduits D will be communicated through the passage H to the cylinder G and the plston will be further raised to open communication with the conduits D, D and D Thus the construction is such as to respond only to sustained demand and not to instantaneous fluctuations produced by a sudden opening of the throttle.

As has been stated, it is impossible to avoid fallin out of suspension of some of the liquid uel, as for instance where the deflection of the throttle causes the stream to impinge upon one side of the conduit C. There might thus be danger that more of this fuel would be drawn into one or another of the conduits E, E and E', but this is avoided by extending the inlet ends of said conduits inward beyond the walls of the conduit C, which latter is preferably enlarged in area to avoid restrlction by such inward projections.

\Vhen the demand is such as to open communication between the conduit C and the conduits D, D and D without utilizing the latter conduits to their full Capacity, the lowered velocity in such conduits may cause the dropping out of some of the fuel. Also at the discharge ends of the conduits where entering the. cylinder block, the increased cross-sectional area over that of the primary conduit will lower the velocity and tend to drop out some of the fuel or to cause loadin This defect is avoided by so designing eac 1 of the conduits D, D and D and the passage I within the engine block that any liquid fuel falling out of suspension will drain towards one point. At this point J the provision is made for withdrawing the fuel and injecting it again into the high velocity portion of the stream. Thus as shown in Figure 2, a small conduit K extends from the point J outward and is then return bent at L to extend centrally into the discharge end of the conduit E. The hi h velocity of the mixture passing through t his conduit will produce an ejector effect that will draw in the liquid fuel and reatomize it in the gaseous stream.

In the modification shown in Figure 3. an alternative construction of means for retaining fuel dropping out of suspension is illustrated. As shown, the drainage point J for the conduits I and D is connected to conduct the fluid into the throat M of a Ventrui bushing N at the discharge end of the conduit E. Thus all fuel collecting at J will be reatomized and returned into the gaseous stream.

From the description above given it will be understood that in the normal operation of the engine, any low demand will be supplied exclusively by mixture passing through the primary conduits E, E and E Any increased demand, if sufiiciently long sustained, will cause the rise of the piston valve F and the opening of communication between the conduit C and the conduits D, D and D The degree of mening will depend upon the demand an at maximum demand said conduits will be fully opened. On the other hand, sudden fluctuation in manifold pressure will not produce an instantaneous opening of the piston valve F, and therefore, the high velocity in the conduits E, E and E is at all times maintained. It will also be noted that the enlargement of the passage adjacent to the inlet valve will cause any fuel not thoroughly atomized to drop out and to be returned in a highl atomized condition. Thus the mixture, w en introduced into the explosion chamber, is in the best condition for complete combustion.

What I claim as my invention is:

1. A manifold for internal combustion engines comprising a common inlet portion, a plurality of pairs of conduits symmetrically connected to said common inlet portion, each pair comprising a conduit of relatively small cross-sectional area and a. conduit of greater cross-sectional area, the smaller of said conduits extending radially inward from the walls of said inlet to receive mixture from the central portion thereof, a valve for closing communication between said inlet ortion and the larger of said conduits, an means responsive to sustained increase in demand for opening said valve.

2. A manifold for internal combustion engines comprising a common inlet portion, a plurality of pairs of conduits symmetrically connected to said common inlet portion, each pair being capable of supplying the maximum demand and comprising primary and secondary conduits, means normally closing said secondary conduit under low demand, said means being responsive to sustained increased demand for variably opening said secondary conduit to supplement said primary conduit, said secondary conduit being arranged to drain fuel collecting on the walls'thereof into the stream discharging from said primary conduit.

3. A manifold for internal combustion engines comprising a common inlet portion, a pair of conduits leading from said common inlet portion capable of together supplying the maximum demand, the primary of said conduits being restricted in cross sectional area to maintain a minimum velocity under a minimum demand, said conduits being united adjacent the inlet valve of the engine forming a common assage having a loading point, the secon ary of said conduits being arranged to drain into said loading point, and means for reatomizing and re-introducing the liquid fuel collected at said loaduing the stream discharging from sai conduit.

4. A manifold for internal combustion engines comprising a common inlet portion, a primary conduit of relatively small cross sectional area connected thereto for supplying a mixture under low demand, a secondary conduit of greater cross sectional area connected to said inlet portion and spaced primary above said primary conduit and apistonvalve movab e within said inlet portion and normally closing communication between said inlet portion and said secondary conduit, said piston valve being of a length sufiicient to prevent communication between the inlet ortion and the secondary conduit uponsud en fluctuations in the manifold.

In testimony whereof I affix my signature.

ALANSON P. BRUSH.

oint into V 

